Bump sabre/vobject to 4.4.1

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

diff --git a/3rdparty b/3rdparty
index f6e3fb0265ac03394420525b26ab7f306ae373d5..4921806dfb1c5c309eac60195ed34e2749baf3c1 160000 (submodule)
--- a/3rdparty
+++ b/3rdparty
@@ -1 +1 @@
-Subproject commit f6e3fb0265ac03394420525b26ab7f306ae373d5
+Subproject commit 4921806dfb1c5c309eac60195ed34e2749baf3c1